Laboratory of Central Nervous System Diseases, National Institute of Neurological Disorders and Blindness, National Institutes of Health, Bethesda, MD, USA

Accepted 22 February 2001

It is sometimes forgotten that in the story of bovine spongiform encephalopathy and variant Creutzfeldt-Jakob disease there is but one incontestable fact, that bovine spongiform encephalopathy is the cause of variant Creutzfeldt-Jakob disease. First suggested by their temporospatial association and the distinctive features of variant Creutzfeldt-Jakob disease, the link has since been proved by their equally distinctive and shared biological and molecular features.1–3 All the rest is speculation, more or less plausible according to the arguments advanced and the absence of any satisfactory alternative explanations.

From an epidemiological point of view bovine spongiform encephalopathy has been a classic epidemic and will undoubtedly become a textbook example for students (fig 1). From economic, political, and medical points of view it has been an unmitigated disaster. Why did it begin when it did, and how did it happen?

Summary points

The infectious agent that causes scrapie in sheep crossed the species barrier to bovines to cause bovine spongiform encephalopathy

Changes in the rendering of livestock carcases allowed infectivity to survive and contaminate meat and bone meal in livestock feed, amplifying infection to epidemic proportions

Export of contaminated meat and bone meal and live cattle incubating the disease caused the spread of bovine spongiform encephalopathy to other countries

International regulatory measures are limiting the further spread of bovine spongiform encephalopathy, its entry into the human food chain, and potential secondary human to human spread of variant Creutzfeldt-Jakob disease, so that both diseases should gradually disappear

FIG 1

Chronology of epidemic of bovine spongiform encephalopathy in United Kingdom, 1986-2000

Origin of bovine spongiform encephalopathy: recycled scrapie

The first case of a cow with bovine spongiform encephalopathy was diagnosed in 1986, and because of the long …

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